# Reference - Code API

Here's the reference or code API, the classes, functions, parameters, attributes, and
all the FastAPI parts you can use in your applications.

If you want to **learn FastAPI** you are much better off reading the

  AnnotationTarget.FIELD,
  AnnotationTarget.LOCAL_VARIABLE,
  AnnotationTarget.VALUE_PARAMETER,
  AnnotationTarget.CONSTRUCTOR,
  AnnotationTarget.FUNCTION,
  AnnotationTarget.PROPERTY_GETTER,
  AnnotationTarget.PROPERTY_SETTER,
  AnnotationTarget.TYPEALIAS,
)
@RequiresOptIn(level = RequiresOptIn.Level.ERROR)

If you want to secure your API, there are several better things you can do, for example:

* Make sure you have well defined Pydantic models for your request bodies and responses.
* Configure any required permissions and roles using dependencies.

                    // words, this receiver expression should be pointing at an unqualified name of a class, whose class ID is
                    // `outerClassId`.
                    if (receiverExpression == expression) {
                        // If there is still an outer class, then return symbol of that class

val codenarcVersion = if (isGroovy4) "3.1.0-groovy-4.0" else "3.1.0"
val spockVersion = if (isGroovy4) "2.2-groovy-4.0" else "2.2-groovy-3.0"
val asmVersion = "9.7"
// To try out better kotlin compilation avoidance and incremental compilation
// with -Pkotlin.incremental.useClasspathSnapshot=true
val kotlinVersion = providers.gradleProperty("buildKotlinVersion")
    .getOrElse(embeddedKotlinVersion)

In that case, it could be better to have only 2 servers and use a higher percentage of their resources (CPU, memory, disk, network bandwidth, etc).

Calling this program outputs:

```
John Doe
```

The function does the following:

* Takes a `first_name` and `last_name`.
* Converts the first letter of each one to upper case with `title()`.
* <abbr title="Puts them together, as one. With the contents of one after the other.">Concatenates</abbr> them with a space in the middle.

```Python hl_lines="2"
{!../../../docs_src/python_types/tutorial001.py!}
```

### Edit it

And if you click it, you have a little authorization form to type a `username` and `password` (and other optional fields):

<img src="/img/tutorial/security/image02.png">

!!! note
    It doesn't matter what you type in the form, it won't work yet. But we'll get there.

### TLS with SNI Extension

**Only one process** in the server can be listening on a specific **port** in a specific **IP address**. There could be other processes listening on other ports in the same IP address, but only one for each combination of IP address and port.

TLS (HTTPS) uses the specific port `443` by default. So that's the port we would need.

That means that, for example, to apply authentication to all the *path operations* in a router it would end up being done in a different file, instead of keeping related logic together.